CPAP facts, information and advice - what you need to know

All you need to know about CPAP therapy

CPAP therapy is used by millions of people worldwide every night. Here we explain what it is, how it works, and how you can get equipment should you need it.

What is CPAP therapy?

A typical CPAP set up showing machine, mask and tubing

CPAP stands for Continuous Positive Airway Pressure. It works by blowing air into the user's airway, which creates positive pressure. This helps keeps the airway open and free of obstructions such as loose tissue.

It is the primary treatment method for Obstructive Sleep Apnoea (OSA). OSA sees the person's airway repeatedly become blocked during the night. These breathing pauses disrupt sleep. The positive pressure in the airway provided stops this happening, and allows normal sleep.

CPAP is a therapy for OSA; it is not a cure. Wherever possible it should be used whenever the patient sleeps, as without it OSA will return instantly. It has been compared to water; you can drink water every day, but the day you stop you will dehydrate.

Numerous clinical studies have proven the effectiveness of CPAP. Sleepiness, and the risk of heart problems are reduced by the therapy. Therefore most OSA diagnoses have CPAP has the first treatment option.

What equipment does CPAP use?

CPAP therapy consists of a machine to blow air, a mask worn on the face, and a tube to connect them.

The mask will cover the nose, the mouth, or a combination of the two depending on the individual's requirements.

The machines are typically around the size of a shoe box, but as the technology advances are becoming ever smaller. Travel machines, such as the Transcend range, are little bigger than a computer mouse.

The masks come in all shapes and sizes to meet different requirements. CPAP gained an early reputation for being uncomfortable, but mask design has improved hugely in recent years. Most masks are now very ergonomic, with minimal skin contact. They also come in different materials; previously plastic, there are now gel and even fabric cushions available. As a result, the therapy is now far more comfortable with a suitable option for almost every patient.

Some systems will include a humidifier (or can have one added). This warms the air, which many find more comfortable. They also add moisture to the air, to reduce the likelihood of the mouth drying out from the extra air passing through. You can find out more about humidification here.

The prevalence of CPAP

Obstructive Sleep Apnoea is among the most common sleep disorders. Estimates about its prevalence vary from 5% up to 20% of the adult population, and becomes more common with age.

An estimated 100,000 sleep studies are conducted per year by the NHS. This leaves millions without a formal diagnosis.

Private, in-home sleep studies help make up some of the shortfall in studies, however.

It is thought only around 10% of those with OSA have been formally diagnosed. A CPAP machine will have been issued to the majority of these.

Therefore, it is estimated that in the UK, around 250,000 to 500,000 people will have been prescribed CPAP therapy. This number grows every year, as the awareness of OSA increases.

The difference between Auto-CPAP and Fixed

A fixed-pressure CPAP machine (often simply called "CPAP") stays at one constant pressure level throughout the night.

An automatic CPAP machine (often called "Auto-CPAP" or "APAP") adjusts the pressure throughout the night.

With a fixed-pressure machine, a sleep consultant typically determines the pressure setting for the individual. As OSA severity can change over time, so does the pressure required to treat it. Therefore, fixed-pressure machines require regular re-assessment to ensure the therapy level is appropriate.

An Automatic machine has numerous sensors built-in to assess what pressure level the patient requires at any given time. This makes them the more popular choice for several reasons.

As they adjust pressures automatically, they do not require regular re-assessment.

On average the pressure is lower, and therefore more comfortable, over the course of a night. An Automatic machine only increases the pressure when it detects a problem. They are able to provide more detailed feedback about the therapy as they have more sensors.

On the last point; fixed-pressure machines can typically only show usage times, and leakage rates on their data recordings. Auto-CPAP machines can typically additionally show pressure changes, and significantly - AHI. AHI is the measurement of OSA severity, and therefore with an Automatic machine it is easier to see statistically if OSA is being treated successfully.